When does a fetus start growing hair? Most fetuses will grow hair around 4 months old, while some fetuses do not start growing hair until 6 months old. From the age of three to four months, the fetus\’ hair, eyelashes, and nails begin to grow, and even the fuzz on the face is secretly growing. By five months, the hair will cover the fetal scalp as quickly as possible. By seven months, except for the sparse hair on the back of the head, the rest of the baby\’s head will be the same as that of a newborn. Recommended parenting books: Preschool Child Development Psychology epub+mobi+azw3 The sooner or later the fetus will grow hair is related to heredity and eating habits. Therefore, if you want the fetus to develop normally, you must pay attention to your diet during pregnancy and have a balanced diet.